<title>Ambiguous line width</title>

<div style="background: yellow; width: 10em; height: 10em; position: absolute">
  <div style="position: absolute; top: 0; left: 0; height: 0.5em; width: 1em; background: blue"></div>
  <div style="position: absolute; top: 0.5em; left: 0; height: 2em; width: 10em; background: aqua"></div>

  <span style="position: absolute; top: 2.5em; left: 0; height: 1em; width: 4em; background: maroon;"></span>

</div>
